GroEl/Es is a chaperone protein complex present in many bacteria including E.coli. Gro El encodes a barrel-like structure and requires the “lid” protein GroEs to function properly. Unfolded proteins bind to a hydrophobic patch near the inner lip of GroEL, inducing GroEs to bind. This patch is then “hidden” in a conformational change, exposing the protein to the hydrophilic environment of the protein interior. In the tight space, the entropic cost of protein folding is lowered and proteins will fold and unfold repeatedly until reaching the native structure. The protein is then released into the cytoplasm.